// A File represents an open PE file.
  type File struct {
	FileHeader
	OptionalHeader any // of type *OptionalHeader32 or *OptionalHeader64
	Sections       []*Section
	Symbols        []*Symbol    // COFF symbols with auxiliary symbol records removed
	COFFSymbols    []COFFSymbol // all COFF symbols (including auxiliary symbol records)
	StringTable    StringTable

	closer io.Closer
  }

   ...
   k+0:  regular sym k
   k+1:    1st aux symbol for k
   k+2:    2nd aux symbol for k
   k+3:  regular sym k+3
   k+4:    1st aux symbol for k+3
   k+5:  regular sym k+5
   k+6:  regular sym k+6
   ...

// Section characteristics flags.
const (
	IMAGE_SCN_CNT_CODE               = 0x00000020
	IMAGE_SCN_CNT_INITIALIZED_DATA   = 0x00000040
	IMAGE_SCN_CNT_UNINITIALIZED_DATA = 0x00000080
	IMAGE_SCN_LNK_COMDAT             = 0x00001000
	IMAGE_SCN_MEM_DISCARDABLE        = 0x02000000
	IMAGE_SCN_MEM_EXECUTE            = 0x20000000
	IMAGE_SCN_MEM_READ               = 0x40000000
	IMAGE_SCN_MEM_WRITE              = 0x80000000
)

// COFFSymbolAuxFormat5 describes the expected form of an aux symbol
// attached to a section definition symbol. The PE format defines a
// number of different aux symbol formats: format 1 for function
// definitions, format 2 for .be and .ef symbols, and so on. Format 5
// holds extra info associated with a section definition, including
// number of relocations + line numbers, as well as COMDAT info. See
// https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#auxiliary-format-5-section-definitions
// for more on what's going on here.
type COFFSymbolAuxFormat5 struct {
	Size           uint32
	NumRelocs      uint16
	NumLineNumbers uint16
	Checksum       uint32
	SecNum         uint16
	Selection      uint8
	_              [3]uint8 // Padding
}

// These constants make up the possible values for the 'Selection'
// field in an AuxFormat5.
const (
	IMAGE_COMDAT_SELECT_NODUPLICATES = 1
	IMAGE_COMDAT_SELECT_ANY          = 2
	IMAGE_COMDAT_SELECT_SAME_SIZE    = 3
	IMAGE_COMDAT_SELECT_EXACT_MATCH  = 4
	IMAGE_COMDAT_SELECT_ASSOCIATIVE  = 5
	IMAGE_COMDAT_SELECT_LARGEST      = 6
)

// COFFSymbolReadSectionDefAux returns a blob of axiliary information
// (including COMDAT info) for a section definition symbol. Here 'idx'
// is the index of a section symbol in the main COFFSymbol array for
// the File. Return value is a pointer to the appropriate aux symbol
// struct. For more info, see:
//
// auxiliary symbols: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#auxiliary-symbol-records
// COMDAT sections: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#comdat-sections-object-only
// auxiliary info for section definitions: https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#auxiliary-format-5-section-definitions
//
func (f *File) COFFSymbolReadSectionDefAux(idx int) (*COFFSymbolAuxFormat5, error) {

...
}